Interpretive Summary: Heparanase (HPSE) and Hyaluronidase (HYAL) 1 and 2 have been shown to be biologically relevant in ovarian and placental activity. Therefore it was the objective of this study to determine if polymorphisms within these genes were associated with reproduction and production events. Using a Landrace-Duroc-Yorkshire population, associations between single nucleotide polymorphisms (SNPs) within HPSE, HYAL1, and HYAL2 were determined. Both age at puberty and weaning-to-estrus interval were associated with a SNP in HYAL2 potentially suggesting a relationship of this SNP with fecundity. Birth weights and litter size components were associated with SNP in HPSE, HYAL1, and HYAL2. Because SNPs within HPSE and HYAL 1 and 2 were associated with reproductive and productive events, it could be very useful to utilize these SNPs or others in linkage disequilibrium for marker-assisted selection protocols for breeding females to determine potential fertility, litter size capabilities, and/or piglet survivability prior to introduction into the breeding system.

Technical Abstract:
Background: The ovary and placenta are dynamic structures requiring constant modification both structurally and through cell-cell communication capabilities. The extracellular matrix and basement membranes are primarily composed of a mileu of glycosaminoglycans, including heparan sulfate and hyaluronan. Heparanase and hyaluronidases are responsible for degrading heparan sulfate and hyaluronan, respectively. Therefore, the objective of this study was to evaluate the relationship of SNPs distinct to HPSE, HYAL1, and HYAL2 with measurements of reproduction and production traits in swine.
Results: Single trait associations were performed on a Landrace-Duroc-Yorkshire population using SNPs discovered and identified in HPSE, HYAL1, and HYAL2. Analyses were conducted on an extended pedigree and SNPs were found to be associated with reproductive traits. SNPs within HPSE were associated with age at puberty, birth weight measurements, and number weaned. A single HYAL1 SNP was associated with litter size traits. While one HYAL2 SNP was associated with the reproductive traits of age at puberty and weaning-to-estrus interval, another HYAL2 SNP was associated with litter birth weight.
Conclusions: Functionally, HPSE and HYAL1-2 have been shown to participate in events related to ovarian and placental activity. These physiological events impact fertility and reproduction, as well as mechanisms involved in placental development and function. SNPs from these studies could potentially be used in MAS to identify animals with improved potential for sow lifetime productivity as measured by age at puberty and weaning-to-estrus interval, as well as piglet survivability, thereby contributing to a greater number of pigs/sow/year.